Collapsible fuel tank



c. KURRLE 2,355,084

COLLAPSIBLE FUEL TANK Filed May 5, 1943 Patented Aug. 1944 UNITED STATESPATENT OFFICE COLLAPSIBLE FUEL TANK Christian Kurrle, Dayton, OhioApplication May 5, 1943, Serial No. 435,723

(or. rat-0.5)

3 Claims.

(Granted under the act of amended April 30, 1928;

The invention described herein may be manufactured and used by or forGovernment for governmental purposes, without the payment to me of anyroyalty thereon.

This invention relates to auxiliary fuel tanks for airplanes, and itsprincipal object is to provide a collapsible fuel tank which will occupyonly a small fraction of the shipping space required for metal tanks ofthe same capacity so that many more of the tanks may be shipped abroadto various theaters of the Second World War. A further object is to savestrategic materials. It will be understood that during this war pursuitor fighter type airplanes are frequently sent on long missions requiringflights far beyond their normal radii of action, and that for suchmissions one or more auxiliary tanks are carried, usually of steel oraluminum and suspended from the bomb racks under the wings, each tankbeing connected by quick-detachable tubing to the intake side of theengine and being dropped when empty. Ordinarily such tanks are ,neverrecovered, hence each extended flight means the loss of one or moreexpensive metal tanks which must be replaced by a shipment originatingfrom the United States before another mission is undertaken. Theexceedingly high cost of merely supplying the necessary tanks to a groupof airplanes operating in a remote theater is apparent withoutelaboration.

In the accompanying drawing forming a part of this specification- Figure1 is a side elevation of bodiment of the invention;

Figure 2 is a cross section on ure 1;

Figure 3 is a cross section on line 3-3 ure 1;

Figure 4 is an enlarged detail in section of the bulkhead construction;and

Figure 5 is an enlarged detail of one of the seams.

Referring particularly to the drawing, the preferred tank body is madeof a plurality of gores 6 of cotton duck, canvas or other relativelystill, porous cotton cloth, so cut and sewed together as to provide ahollow body 1 having the well known form of a dirigible, i. e., circularin cross section but larger at one end than at the other, and uniformlystreamlined except for the fittings and attachments to be described. Theillustrative body is composed of eight cotton duck or canvas gores sewedtogether along their longitudinal edges to form seams 8, but there maybe moreor fewer gores, the number'that is desired being proportional tothe size of the tank. As shown in Fig. 3,

the preferred emline 2-2 of Figof Fig- March 3, 1883, as 370 O. G. 757)point, at both ends of the body. Each seam 8 has its free edges coveredby cotton tape 9 stitched'as at In, Fig. 5. The cotton tape provides astiffening means as well as a reinforcement for the seam. The gores areassembled and sewed together with the tank body wrong side out and whenall the stitching is complete except for a length of about two feetalong one seam, the body is turned right side out by pulling first oneend, then the other, through the opening. Then the fittings to bedescribed are installed, and the opening of the last seam is closed bystitching, as indicated at I I, Figure 2. I

To reinforce the tank and obviate. any tendency to collapse laterally,two or more bulkheads l2,

l3 are placed inside the tank. Each bulkhead is a vertical partitionsnugly fitting the inside of the tank and dividing the tank intocompartments; and to permit the liquid fuel to flow from one compartmentto another, each bulkhead has several openings l4, l5, I6. The twobulkheads are exactly alike except for size, hence the followingdetailed description of one bulkhead applies also to the other. Bulkheadl2 consists of two circular plies l1, l8 of canvas united by stitching I9, with the edges of the two plies turned at right angles but inopposite directions, see Figure 4. A strip of cotton webbing 20encircles the outtumed edges of the piles and is stitched thereto asindicated at 20a. Reinforcing strips or ribs 2l, each made of a strip ofcanvas sewed along its edges to the bulkhead, with a looped or gatheredcentral portion extending for the entire length of each rib, providestiffening means for the bulkheads. Both bulkheads are secured insidethe body by stitching 22 uniting the peripheries of the bulkheads to thetank walls.

A filling opening 23 is made near the forward or larger end of thebody,.and the usual metal collar 24 and cap 25 employed on fuel tanksare also provided. 'IA metal fitting 25 providing a vent and two metalcouplings 21, 28-for the fuel tubing 29 are alsoshown. Two fuel tube'couplings are desirable to permit use of a single model of tank witheither of two well known types of pursuit planes. Reinforcing strips ofcanvas 30, 3| are sewed on the outside of the body to make possible thesecure attachment of metal hangers the seams all converge to a commonmeeting 32 which engage with some conventional bomb shackle, hereindicated diagrammatically at 33. By tripping the release (not shown)the tank may be jettisoned by the pilot while the airplane is in fullflight. The bulkheads reinforce the tank in the areas adjacent theplanes of hangers 32, so that collaps or deformation of the body due tostresses imposed by the load is obviated.

To prepare a collapsed tank for holding -fuel a resin glue ispouredthrough the filling opening 23 and then all openings are closed.Various tacky substances neutral to aromatic fuels and capable ofpenetrating the porous tank walls and hardening to waterproof andstiflen the walls may be used. A suitable resin glue is Plaskon gluemade by The ,Plaskon 00., Toledo, Ohio. Then the body is rotated andtumbled so that the resinous glue spreads over all the interiorsurfaces, including the baflles and ribs, and air pressure is applied,for example by meansof a hose (not shown) leading to a compressed airtank (not shown) and coupled to one of the couplings 21, 28. Airpressure builds up on the inside and when the pressure is high enoughthe air escapes through the pores of the canvas, it particles of theglue, which gradually coats the entire outside of the tank as well asthe inside. Then the compressed air line is disconnected, and the bodyis allowed to dry and set. Finally a coat of the resinous glue isbrushed or sprayed on the outside walls and then allowedto dry and set.Th result is that all the walls, bulkheads, ribs and seams are made verystiff, so that the body is resistant to any stresses it may encounterwhile in service. The seams 8 when stifiened by the glue providelongitudinal ribs which are especially important to maintain thestreamlined shape of the tank during flight, while the bulkheads becomestiff enough to resist lateral or crushing stresses and to preventdeformation due to the weight of the fuel and the reaction of thsuspension of the body from hangers.

The described fuel expensive than aluminum and being made of cotton willeffect a large saving in strategic materials. Usually its capacity willbe 75 gallons but tanks containing 125 gallons or more may be made. Asfifteen collapsed tanks may be shipped in the space occupied by onemetal tank, a huge saving in shipping space may be effected, which is ofthe utmost importance due to the submarine menace. Furthermore makingthe collapsed tanks is easily accomplished by any small manufacturerprovided with sewing machines, textile shears, etc.; hence themanufacture of the tanks tank is lighter and much less.

carrying with presents no problem and may be undertaken at a largenumber of shops and small factories.

Obviously the present invention may assume various forms neitherdescribed nor shown.

What I claim is: 1. An auxiliary fuel tank for airplanes comprising a.streamlined, hollow body made entirely of longitudinally extending goresof cotton duck or similar heavy, porous, textile material, sewedtogether along their longitudinal edges with the seams projectinginwardly to form longitudinal ribs; bulkheads secured inside the body;said bulkheads being of the same material as the body and havingperforations for passage of the fuel and reinforcing lateral ribsalso'of the same material; the entire body including the longitudinalribs, the bulkheads, and the lateral ribs bein stiffened and sealed by aresinous, waterproof glue which is neutral to aromatic fuels; thestillness being such that the tank maintains its original shape whenpartly empty and subjected to the aerodynamic forces arising duringflight.

2. An auxiliary tank for aircraft comprising a body wholly composed ofgores of canvas, cotton duck or the like sewed together to form astreamlined container larger at one end than at the other and circularin cross section throughout its length; the seams of the gores beingturned inwardly to provide ribs, said ribs extending longitudinally andconverging to a common meeting point inside the body at both ends; the ventire body being sealed and stiffened by means of a resin gluepermeating all the pores and coating all surfaces, inside and out; theconverging ribs reinforcing the ends and substantially preventingcollapse or deformation under the stresses set up during fligh 3. Theinvention according to claim 2 wherein hangers are secured tothe upperside of the body to permit suspension of the tank from the airplane; andpartitions or. bulkheads made oi. the same material as the body areplaced inside the body to reinforce and prevent collapse thereof due tothe stresses imposed by the weight of the fuel acting at the points ofsuspension.

CHRISTIAN KURRLE.

